The role of the facet capsular ligament in providing spinal stability

Abstract

Low back pain (LBP) is the most common type of pain in America, and spinal instability is a primary cause. The facet capsular ligament (FCL) encloses the articulating joints of the spine and is of particular interest due to its high innervation – as instability ensues, high stretch values likely are a cause of this pain. Therefore, this work investigated the FCL's role in providing stability to the lumbar spine. A previously validated finite element model of the L4-L5 spinal motion segment was used to simulate pure moment bending in multiple planes. FCL failure was simulated and the following outcome measures were calculated: helical axes of motion, range of motion (ROM), bending stiffness, facet joint space, and FCL stretch. ROM increased, bending stiffness decreased, and altered helical axis patterns were observed with the removal of the FCL. Additionally, a large increase in FCL stretch was measured with diminished FCL mechanical competency, providing support that the FCL plays an important role in spinal stability.

KEYWORDS:

• finite element model
• lumbar spine
• facet joint
• instability
• coupled motion

Acknowledgments

The authors would like to acknowledge Hugo Giambini, PhD, Miranda Shaw, PhD, and Ryan Breighner, PhD for their aid in the development of the model.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding provided through National Institute of Child Health and Human Development [K12HD073945], National Institute of Arthritis and Musculoskeletal and Skin Diseases [T32AR050938], and Musculoskeletal Training Grant, and National Institute of Biomedical Imaging and Bioengineering [U01EB016638].